//
// Created by lz on 2021/2/24.
//

#ifndef MYWEBLIB_BASE_ATOMIC_H_
#define MYWEBLIB_BASE_ATOMIC_H_

#include "base/noncopyable.h"
#include <cstdint>

namespace lzweb
{
	namespace detail
	{
		template<typename T>
		class AtomicIntegerT : noncopyable
		{
		 public:
			AtomicIntegerT()
			:value_(0)
			{
			}
			// uncomment if you need copying and assignment
			//
			// AtomicIntegerT(const AtomicIntegerT& that)
			//   : value_(that.get())
			// {}
			//
			// AtomicIntegerT& operator=(const AtomicIntegerT& that)
			// {
			//   getAndSet(that.get());
			//   return *this;
			// }

			T get()
			{
				// in gcc >= 4.7: __atomic_load_n(&value_, __ATOMIC_SEQ_CST)

				// T __sync_val_compare_and_swap (T* __p, T __compVal, T __exchVal, ...);
				// This function compares the value of __compVal to the value of the variable that __p points to.
				// If they are equal, the value of __exchVal is stored in the address that is specified by __p;
				// otherwise, no operation is performed.
				return  __sync_val_compare_and_swap(&value_,0,0);

			}

			T getAndAdd(T x)
			{
				// in gcc >= 4.7: __atomic_fetch_add(&value_, x, __ATOMIC_SEQ_CST)
				return __sync_fetch_and_add(&value_,x);
			}

			T addAndGet(T x)
			{
				return getAndAdd(x) + x;
			}

			T incrementAndGet()
			{
				return addAndGet(1);
			}
			T decrementAndGet()
			{
				return addAndGet(-1);
			}

			void add(T x)
			{
				getAndAdd(x);
			}

			void increment()
			{
				incrementAndGet();
			}

			void decrement()
			{
				decrementAndGet();
			}

			T getAndSet(T newValue)
			{
				// in gcc >= 4.7: __atomic_exchange_n(&value_, newValue, __ATOMIC_SEQ_CST)
				return __sync_lock_test_and_set(&value_,newValue);
			}

		 private:
			//一般在多线程共享变量需要加volatile
			volatile T value_;
		};
	}// namespace detail

	using AtomicInt32 = detail::AtomicIntegerT<int32_t>;
	using AtomicInt64 = detail::AtomicIntegerT<int64_t>;
}// namespace lzweb





#endif //MYWEBLIB_BASE_ATOMIC_H_
